A wide variety of cooking devices have been provided in the past. The conventional oven is illustrative of such cooking devices. Simple Ovens in various forms have been in use for centuries in homes, commercial bakeries, institutional kitchens and restaurants.
Conventional ovens have been provided in a variety of models and sizes, for example, a permanent, built-in style, mounted in cabinetry, together with or independent of a stove top unit. Conventional ovens have also been provided of a portable design. While the conventional oven remains a basic essential cooking unit in the home as well as restaurants or the like, conventional ovens do have their shortcomings. Conventional ovens, for example, tend to cook slowly and thus consume a good deal of the user's time.
Attempts have been made to overcome this problem; for example, microwave ovens have become popular. While microwave ovens cook rapidly, they too have their shortcomings. For example, it is difficult to brown food in a microwave oven.
Other attempts at solving the slowness of conventional ovens has been to include a circulating fan to move the air in the oven. While such circulating fans have provided more rapid cooking, the time required is still very substantial. Such existing ovens perform their tasks in a similar way. The majority of such cooking devices consist of a rectangular oven, usually equipped with a plurality of racks, much like that found in conventional in-home ovens. Often at the rear of the oven is a squirrel-cage type blower which draws the air through a hole in the interior rear wall and blows the air out to the sides, where is it directed to perforations in the two interior side walls. This pressurized air is then forced through the perforations toward the rear center of the oven enclosure, where it is drawn into the blower intake hole and re-circulated, thereby completing a closed loop. An oven produced by Rair follows the above pattern with the exception of circulating the air through a cylindrical chamber with its axis positioned horizontally.
Air velocities within the cooking chamber of such ovens vary widely, depending on the proximity to the blower intake and the air inlet holes. The velocities are generally the highest just in front of the blower intake. A typical average airspeed found in a commercial restaurant convection oven is approximately 350 feet per minute.
Various means of heating the air are used, usually employing natural gas heat exchangers in the sides of the oven or electrical tubular heating elements, like those found in conventional electric household ovens.
Another rapid cooking device has been the deep fat fryer. Such fryers are typically used to prepare French fries, breaded shrimp, fried chicken and the like. Deep fat fryers will typically cook food pieces in from one to five minutes. Deep fat fryers brown the product and develop desirable flavor characteristics. Deep fat fryers, however, also have inherent disadvantages. One such inherent disadvantage is the fact that the cooked food product has very high levels of fats, thus increasing the caloric content as well as the potential adverse effects on the consumer's circulatory system.